Gas distribution assembly for improved pump-purge and precursor delivery

ABSTRACT

Gas injector inserts having a wedge-shaped housing, at least one first slot and at least one second slot are described. The housing has a first opening in the back face that is in fluid communication with the first slot in the front face and a second opening in the back face that is in fluid communication with the second slot in the front face. Each of the first slot and the second slot has an elongate axis that extends from the inner peripheral end to the outer peripheral end of the housing. The gas injector insert is configured to provide a flow of gas through the first slots at supersonic velocity. Gas distribution assemblies and processing chambers including the gas injector inserts are described.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/444,543, filed Jun. 18, 2019, which claims priority to U.S.Provisional Application No. 62/686,398, filed Jun. 18, 2018, the entiredisclosure of which is hereby incorporated by reference herein.

TECHNICAL FIELD

Embodiments of the disclosure generally relate to an apparatus forsemiconductor wafer processing. More particularly, embodiments of thedisclosure relate to gas injector inserts and gas distributionassemblies with a gas injector insert that provides improved pump-purgeoperation and precursor delivery.

BACKGROUND

Atomic Layer Deposition (ALD) and Plasma-Enhanced ALD (PEALD) aredeposition techniques that offer control of film thickness andconformality in high-aspect ratio structures. Due to continuouslydecreasing device dimensions in the semiconductor industry, there isincreasing interest and applications that use ALD/PEALD. In some cases,only PEALD can meet specifications for desired film thickness andconformality.

Semiconductor device formation is commonly conducted in substrateprocessing platforms containing multiple chambers. In some instances,the purpose of a multi-chamber processing platform or cluster tool is toperform two or more processes on a substrate sequentially in acontrolled environment. In other instances, however, a multiple chamberprocessing platform may only perform a single processing step onsubstrates; the additional chambers are intended to maximize the rate atwhich substrates are processed by the platform. In the latter case, theprocess performed on substrates is typically a batch process, wherein arelatively large number of substrates, e.g. 25 or 50, are processed in agiven chamber simultaneously. Batch processing is especially beneficialfor processes that are too time-consuming to be performed on individualsubstrates in an economically viable manner, such as for atomic layerdeposition (ALD) processes and some chemical vapor deposition (CVD)processes.

In large spatial ALD processing chambers, reactive gases can be draggedbetween process regions resulting in gas phase mixing of the reactivegases. Additionally, reaction byproducts can be dragged through the gascurtains separating process regions.

Therefore, there is a need in the art for apparatus to improveseparation of process gases in a spatial ALD processing chamber.

SUMMARY

One or more embodiments of the disclosure are directed to gas injectorinserts comprising a wedge-shaped housing having a back face and frontface, an inner peripheral end and an outer peripheral end defining alength and elongate axis, and a first side and a second side defining awidth, the width increasing from the inner peripheral end to the outerperipheral end. A first opening is in the back face of the housing. Thefirst opening is in fluid communication with at least one first slot inthe front face of the housing. The first slot has an elongate axisextending from a first end near the inner peripheral end to a second endnear the outer peripheral end. A second opening is in the back face ofthe housing. The second opening is in fluid communication with at leastone second slot in the front face of the housing. The second slot has anelongate axis extending from a first end near the inner peripheral endto a second end near the outer peripheral end.

Additional embodiments of the disclosure are directed to gas injectorinserts comprising a wedge-shaped housing having a back face and frontface, an inner peripheral end and an outer peripheral end defining alength and elongate axis, and a first side and a second side defining awidth. The width increases from the inner peripheral end to the outerperipheral end. A first opening is in the back face of the housing. Thefirst opening is in fluid communication with four first slots in thefront face of the housing. The first slots have elongate axes extendingfrom a first end near the inner peripheral end to a second end near theouter peripheral end. A second opening is in the back face of thehousing. The second opening is in fluid communication with three secondslots in the front face of the housing. The second slots have elongateaxes extending from a first end near the inner peripheral end to asecond end near the outer peripheral end. Each of the first slots isspaced from adjacent first slots by a second slot and a gas flowingthrough the first slot exits the housing at supersonic velocity.

BRIEF DESCRIPTION OF THE DRAWING

So that the manner in which the above recited features of the presentdisclosure can be understood in detail, a more particular description ofthe disclosure, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this disclosure and are therefore not to beconsidered limiting of its scope, for the disclosure may admit to otherequally effective embodiments.

FIG. 1 shows a cross-sectional view of a batch processing chamber inaccordance with one or more embodiment of the disclosure;

FIG. 2 shows a partial perspective view of a batch processing chamber inaccordance with one or more embodiment of the disclosure;

FIG. 3 shows a schematic view of a batch processing chamber inaccordance with one or more embodiment of the disclosure;

FIG. 4 shows a schematic view of a portion of a wedge shaped gasdistribution assembly for use in a batch processing chamber inaccordance with one or more embodiment of the disclosure;

FIG. 5 shows a schematic view of a batch processing chamber inaccordance with one or more embodiment of the disclosure;

FIG. 6 shows a gas distribution assembly with openings for gas injectorinserts in accordance with one or more embodiment of the disclosure;

FIG. 7 shows a top perspective view of a gas injector insert inaccordance with one or more embodiment of the disclosure;

FIG. 8 shows a bottom perspective view of a gas injector insert inaccordance with one or more embodiment of the disclosure;

FIG. 9 shows a bottom view of a gas injector insert in accordance withone or more embodiment of the disclosure;

FIG. 10 shows a cross-sectional view of the gas injector insert of FIG.7 taken along line 10-10;

FIG. 11 shows a cross-sectional view of the gas injector insert of FIG.7 taken along line 11-11;

FIG. 12 shows a cross-sectional view of the gas injector insert of FIG.7 taken along line 12-12;

FIG. 13 shows a cross-sectional view of the gas injector insert of FIG.7 taken along line 13-13;

FIG. 14 shows a bottom perspective view of a top plate of a gas injectorinsert in accordance with one or more embodiment of the disclosure;

FIG. 15A shows a top perspective view of an intermediate plate of a gasinjector insert in accordance with one or more embodiment of thedisclosure;

FIG. 15B shows a bottom perspective view of an intermediate plate of agas injector insert in accordance with one or more embodiment of thedisclosure;

FIG. 15C shows an expanded portion of region 15C from FIG. 15B;

FIG. 16A shows top perspective view of a lower plate of a gas injectorinsert in accordance with one or more embodiment of the disclosure;

FIG. 16B shows an expanded portion of region 16B from FIG. 16A;

FIGS. 17A and 17B show top and bottom perspective view, respectively, ofa lower plate of a gas injector insert in accordance with one or moreembodiment of the disclosure; and

FIGS. 18A and 18B show cross-sectional view of a gas injector insert inaccordance with one or more embodiment of the disclosure.

DETAILED DESCRIPTION

Before describing several exemplary embodiments of the disclosure, it isto be understood that the disclosure is not limited to the details ofconstruction or process steps set forth in the following description.The disclosure is capable of other embodiments and of being practiced orbeing carried out in various ways.

A “substrate”, “substrate surface”, or the like, as used herein, refersto any substrate or material surface formed on a substrate upon whichprocessing is performed. For example, a substrate surface on whichprocessing can be performed include, but are not limited to, materialssuch as silicon, silicon oxide, strained silicon, silicon on insulator(SOI), carbon doped silicon oxides, silicon nitride, doped silicon,germanium, gallium arsenide, glass, sapphire, and any other materialssuch as metals, metal nitrides, metal alloys, and other conductivematerials, depending on the application. Substrates include, withoutlimitation, semiconductor wafers. Substrates may be exposed to apretreatment process to polish, etch, reduce, oxidize, hydroxylate (orotherwise generate or graft target chemical moieties to impart chemicalfunctionality), anneal and/or bake the substrate surface. In addition toprocessing directly on the surface of the substrate itself, in thepresent disclosure, any of the film processing steps disclosed may alsobe performed on an underlayer formed on the substrate as disclosed inmore detail below, and the term “substrate surface” is intended toinclude such underlayer as the context indicates. Thus for example,where a film/layer or partial film/layer has been deposited onto asubstrate surface, the exposed surface of the newly deposited film/layerbecomes the substrate surface. What a given substrate surface compriseswill depend on what materials are to be deposited, as well as theparticular chemistry used.

As used in this specification and the appended claims, the terms“reactive compound,” “reactive gas,” “reactive species,” “precursor,”“process gas,” and the like are used interchangeably to mean a substancewith a species capable of reacting with the substrate surface ormaterial on the substrate surface in a surface reaction (e.g.,chemisorption, oxidation, reduction). For example, a first “reactivegas” may simply adsorb onto the surface of a substrate and be availablefor further chemical reaction with a second reactive gas.

“Atomic layer deposition” or “cyclical deposition” as used herein refersto the sequential exposure of two or more reactive compounds to deposita layer of material on a substrate surface. The substrate, or portion ofthe substrate, is exposed separately to the two or more reactivecompounds which are introduced into a reaction zone of a processingchamber. In a time-domain ALD process, exposure to each reactivecompound is separated by a time delay to allow each compound to adhereand/or react on the substrate surface and then be purged from theprocessing chamber. These reactive compounds are said to be exposed tothe substrate sequentially. In a spatial ALD process, different portionsof the substrate surface, or material on the substrate surface, areexposed simultaneously to the two or more reactive compounds so that anygiven point on the substrate is substantially not exposed to more thanone reactive compound simultaneously. As used in this specification andthe appended claims, the term “substantially” used in this respectmeans, as will be understood by those skilled in the art, that there isthe possibility that a small portion of the substrate may be exposed tomultiple reactive gases simultaneously due to diffusion, and that thesimultaneous exposure is unintended.

As used in this specification and the appended claims, the terms“pie-shaped” and “wedge-shaped” are used interchangeably to describe abody that is a sector of a circle. For example, a wedge-shaped segmentmay be a fraction of a circle or disc-shaped structure and multiplewedge-shaped segments can be connected to form a circular body. Thesector can be defined as a part of a circle enclosed by two radii of acircle and the intersecting arc. The inner edge of the pie-shapedsegment can come to a point or can be truncated to a flat edge orrounded. In some embodiments, the sector can be defined as a portion ofa ring or annulus.

The path of the substrates can be perpendicular to the gas ports. Insome embodiments, each of the gas injector assemblies comprises aplurality of elongate gas ports which extend in a directionsubstantially perpendicular to the path traversed by a substrate, wherea front face of the gas distribution assembly is substantially parallelto the platen. As used in this specification and the appended claims,the term “substantially perpendicular” means that the general directionof movement of the substrates is along a plane approximatelyperpendicular (e.g., about 45° to 90°) to the axis of the gas ports. Fora wedge-shaped gas port, the axis of the gas port can be considered tobe a line defined as the mid-point of the width of the port extendingalong the length of the port.

FIG. 1 shows a cross-section of a processing chamber 100 including a gasdistribution assembly 120, also referred to as injectors or an injectorassembly, and a susceptor assembly 140. The gas distribution assembly120 is any type of gas delivery device used in a processing chamber. Thegas distribution assembly 120 includes a front surface 121 which facesthe susceptor assembly 140. The front surface 121 can have any number orvariety of openings to deliver a flow of gases toward the susceptorassembly 140. The gas distribution assembly 120 also includes an outerperipheral edge 124 which in the embodiments shown, is substantiallyround.

The specific type of gas distribution assembly 120 used can varydepending on the particular process being used. Embodiments of thedisclosure can be used with any type of processing system where the gapbetween the susceptor and the gas distribution assembly is controlled.While various types of gas distribution assemblies can be employed(e.g., showerheads), embodiments of the disclosure may be particularlyuseful with spatial ALD gas distribution assemblies which have aplurality of substantially parallel gas channels. As used in thisspecification and the appended claims, the term “substantially parallel”means that the elongate axis of the gas channels extend in the samegeneral direction. There can be slight imperfections in the parallelismof the gas channels. The plurality of substantially parallel gaschannels can include at least one first reactive gas A channel, at leastone second reactive gas B channel, at least one purge gas P channeland/or at least one vacuum V channel. The gases flowing from the firstreactive gas A channel(s), the second reactive gas B channel(s) and thepurge gas P channel(s) are directed toward the top surface of the wafer.Some of the gas flow moves horizontally across the surface of the waferand out of the processing region through the purge gas P channel(s). Asubstrate moving from one end of the gas distribution assembly to theother end will be exposed to each of the process gases in turn, forminga layer on the substrate surface.

In some embodiments, the gas distribution assembly 120 is a rigidstationary body made of a single injector unit. In one or moreembodiments, the gas distribution assembly 120 is made up of a pluralityof individual sectors (e.g., injector units 122), as shown in FIG. 2.Either a single piece body or a multi-sector body can be used with thevarious embodiments of the disclosure described.

The susceptor assembly 140 is positioned beneath the gas distributionassembly 120. The susceptor assembly 140 includes a top surface 141 andat least one recess 142 in the top surface 141. The susceptor assembly140 also has a bottom surface 143 and an edge 144. The recess 142 can beany suitable shape and size depending on the shape and size of thesubstrates 60 being processed. In the embodiment shown in FIG. 1, therecess 142 has a flat bottom to support the bottom of the wafer;however, the bottom of the recess can vary. In some embodiments, therecess has step regions around the outer peripheral edge of the recesswhich are sized to support the outer peripheral edge of the wafer. Theamount of the outer peripheral edge of the wafer that is supported bythe steps can vary depending on, for example, the thickness of the waferand the presence of features already present on the back side of thewafer.

In some embodiments, as shown in FIG. 1, the recess 142 in the topsurface 141 of the susceptor assembly 140 is sized so that a substrate60 supported in the recess 142 has a top surface 61 substantiallycoplanar with the top surface 141 of the susceptor 140. As used in thisspecification and the appended claims, the term “substantially coplanar”means that the top surface of the wafer and the top surface of thesusceptor assembly are coplanar within ±0.2 mm. In some embodiments, thetop surfaces are coplanar within ±0.15 mm, ±0.10 mm or ±0.05 mm. Therecess 142 of some embodiments supports a wafer so that the innerdiameter (ID) of the wafer is located within the range of about 170 mmto about 185 mm from the center (axis of rotation) of the susceptor. Insome embodiments, the recess 142 supports a wafer so that the outerdiameter (OD) of the wafer is located in the range of about 470 mm toabout 485 mm from the center (axis of rotation) of the susceptor.

The susceptor assembly 140 of FIG. 1 includes a support post 160 whichis capable of lifting, lowering and rotating the susceptor assembly 140.The susceptor assembly may include a heater, or gas lines, or electricalcomponents within the center of the support post 160. The support post160 may be the primary means of increasing or decreasing the gap betweenthe susceptor assembly 140 and the gas distribution assembly 120, movingthe susceptor assembly 140 into proper position. The susceptor assembly140 may also include fine tuning actuators 162 which can makemicro-adjustments to susceptor assembly 140 to create a predeterminedgap 170 between the susceptor assembly 140 and the gas distributionassembly 120. In some embodiments, the gap 170 distance is in the rangeof about 0.1 mm to about 5.0 mm, or in the range of about 0.1 mm toabout 3.0 mm, or in the range of about 0.1 mm to about 2.0 mm, or in therange of about 0.2 mm to about 1.8 mm, or in the range of about 0.3 mmto about 1.7 mm, or in the range of about 0.4 mm to about 1.6 mm, or inthe range of about 0.5 mm to about 1.5 mm, or in the range of about 0.6mm to about 1.4 mm, or in the range of about 0.7 mm to about 1.3 mm, orin the range of about 0.8 mm to about 1.2 mm, or in the range of about0.9 mm to about 1.1 mm, or about 1 mm.

The processing chamber 100 shown in the Figures is a carousel-typechamber in which the susceptor assembly 140 can hold a plurality ofsubstrates 60. As shown in FIG. 2, the gas distribution assembly 120 mayinclude a plurality of separate injector units 122, each injector unit122 being capable of depositing a film on the wafer, as the wafer ismoved beneath the injector unit. Two pie-shaped injector units 122 areshown positioned on approximately opposite sides of and above thesusceptor assembly 140. This number of injector units 122 is shown forillustrative purposes only. It will be understood that more or lessinjector units 122 can be included. In some embodiments, there are asufficient number of pie-shaped injector units 122 to form a shapeconforming to the shape of the susceptor assembly 140. In someembodiments, each of the individual pie-shaped injector units 122 may beindependently moved, removed and/or replaced without affecting any ofthe other injector units 122. For example, one segment may be raised topermit a robot to access the region between the susceptor assembly 140and gas distribution assembly 120 to load/unload substrates 60.

Processing chambers having multiple gas injectors can be used to processmultiple wafers simultaneously so that the wafers experience the sameprocess flow. For example, as shown in FIG. 3, the processing chamber100 has four gas injector assemblies and four substrates 60. At theoutset of processing, the substrates 60 can be positioned between theinjector assemblies 30. Rotating 17 the susceptor assembly 140 by 45°will result in each substrate 60 which is between gas distributionassemblies 120 to be moved to an gas distribution assembly 120 for filmdeposition, as illustrated by the dotted circle under the gasdistribution assemblies 120. An additional 45° rotation would move thesubstrates 60 away from the injector assemblies 30. With spatial ALDinjectors, a film is deposited on the wafer during movement of the waferrelative to the injector assembly. In some embodiments, the susceptorassembly 140 is rotated in increments that prevent the substrates 60from stopping beneath the gas distribution assemblies 120. The number ofsubstrates 60 and gas distribution assemblies 120 can be the same ordifferent. In some embodiments, there is the same number of wafers beingprocessed as there are gas distribution assemblies. In one or moreembodiments, the number of wafers being processed are fraction of or aninteger multiple of the number of gas distribution assemblies. Forexample, if there are four gas distribution assemblies, there are 4×wafers being processed, where x is an integer value greater than orequal to one.

The processing chamber 100 shown in FIG. 3 is merely representative ofone possible configuration and should not be taken as limiting the scopeof the disclosure. Here, the processing chamber 100 includes a pluralityof gas distribution assemblies 120. In the embodiment shown, there arefour gas distribution assemblies (also called injector assemblies 30)evenly spaced about the processing chamber 100. The processing chamber100 shown is octagonal, however, those skilled in the art willunderstand that this is one possible shape and should not be taken aslimiting the scope of the disclosure. The gas distribution assemblies120 shown are trapezoidal, but can be a single circular component ormade up of a plurality of pie-shaped segments, like that shown in FIG.2.

The embodiment shown in FIG. 3 includes a load lock chamber 180, or anauxiliary chamber like a buffer station. This chamber 180 is connectedto a side of the processing chamber 100 to allow, for example thesubstrates (also referred to as substrates 60) to be loaded/unloadedfrom the processing chamber 100. A wafer robot may be positioned in thechamber 180 to move the substrate onto the susceptor.

Rotation of the carousel (e.g., the susceptor assembly 140) can becontinuous or discontinuous. In continuous processing, the wafers areconstantly rotating so that they are exposed to each of the injectors inturn. In discontinuous processing, the wafers can be moved to theinjector region and stopped, and then to the region 84 between theinjectors and stopped. For example, the carousel can rotate so that thewafers move from an inter-injector region across the injector (or stopadjacent the injector) and on to the next inter-injector region wherethe carousel can pause again. Pausing between the injectors may providetime for additional processing steps between each layer deposition(e.g., exposure to plasma).

FIG. 4 shows a sector or portion of a gas distribution assembly 220,which may be referred to as an injector unit 122. The injector units 122can be used individually or in combination with other injector units.For example, as shown in FIG. 5, four of the injector units 122 of FIG.4 are combined to form a single gas distribution assembly 220. (Thelines separating the four injector units are not shown for clarity.)While the injector unit 122 of FIG. 4 has both a first reactive gas port125 and a second reactive gas port 135 in addition to purge gas ports155 and vacuum ports 145, an injector unit 122 does not need all ofthese components.

Referring to both FIGS. 4 and 5, a gas distribution assembly 220 inaccordance with one or more embodiment may comprise a plurality ofsectors (or injector units 122) with each sector being identical ordifferent. The gas distribution assembly 220 is positioned within theprocessing chamber and comprises a plurality of elongate gas ports 125,135, 145 in a front surface 121 of the gas distribution assembly 220.The plurality of elongate gas ports 125, 135, 145 and vacuum ports 155extend from an area adjacent the inner peripheral edge 123 toward anarea adjacent the outer peripheral edge 124 of the gas distributionassembly 220. The plurality of gas ports shown include a first reactivegas port 125, a second reactive gas port 135, a vacuum port 145 whichsurrounds each of the first reactive gas ports and the second reactivegas ports and a purge gas port 155.

With reference to the embodiments shown in FIG. 4 or 5, when statingthat the ports extend from at least about an inner peripheral region toat least about an outer peripheral region, however, the ports can extendmore than just radially from inner to outer regions. The ports canextend tangentially as vacuum port 145 surrounds reactive gas port 125and reactive gas port 135. In the embodiment shown in FIGS. 4 and 5, thewedge shaped reactive gas ports 125, 135 are surrounded on all edges,including adjacent the inner peripheral region and outer peripheralregion, by a vacuum port 145.

Referring to FIG. 4, as a substrate moves along path 127, each portionof the substrate surface is exposed to the various reactive gases. Tofollow the path 127, the substrate will be exposed to, or “see”, a purgegas port 155, a vacuum port 145, a first reactive gas port 125, a vacuumport 145, a purge gas port 155, a vacuum port 145, a second reactive gasport 135 and a vacuum port 145. Thus, at the end of the path 127 shownin FIG. 4, the substrate has been exposed to gas streams from the firstreactive gas port 125 and the second reactive gas port 135 to form alayer. The injector unit 122 shown makes a quarter circle but could belarger or smaller. The gas distribution assembly 220 shown in FIG. 5 canbe considered a combination of four of the injector units 122 of FIG. 4connected in series.

The injector unit 122 of FIG. 4 shows a gas curtain 150 that separatesthe reactive gases. The term “gas curtain” is used to describe anycombination of gas flows or vacuum that separate reactive gases frommixing. The gas curtain 150 shown in FIG. 4 comprises the portion of thevacuum port 145 next to the first reactive gas port 125, the purge gasport 155 in the middle and a portion of the vacuum port 145 next to thesecond reactive gas port 135. This combination of gas flow and vacuumcan be used to prevent or minimize gas phase reactions of the firstreactive gas and the second reactive gas.

Referring to FIG. 5, the combination of gas flows and vacuum from thegas distribution assembly 220 form a separation into a plurality ofprocessing regions 250. The processing regions are roughly definedaround the individual reactive gas ports 125, 135 with the gas curtain150 between 250. The embodiment shown in FIG. 5 makes up eight separateprocessing regions 250 with eight separate gas curtains 150 between. Aprocessing chamber can have at least two processing region. In someembodiments, there are at least three, four, five, six, seven, eight,nine, 10, 11 or 12 processing regions.

During processing a substrate may be exposed to more than one processingregion 250 at any given time. However, the portions that are exposed tothe different processing regions will have a gas curtain separating thetwo. For example, if the leading edge of a substrate enters a processingregion including the second reactive gas port 135, a middle portion ofthe substrate will be under a gas curtain 150 and the trailing edge ofthe substrate will be in a processing region including the firstreactive gas port 125.

A factory interface 280, which can be, for example, a load lock chamber,is shown connected to the processing chamber 100. A substrate 60 isshown superimposed over the gas distribution assembly 220 to provide aframe of reference. The substrate 60 may often sit on a susceptorassembly to be held near the front surface 121 of the gas distributionassembly 120 (also referred to as a gas distribution plate). Thesubstrate 60 is loaded via the factory interface 280 into the processingchamber 100 onto a substrate support or susceptor assembly (see FIG. 3).The substrate 60 can be shown positioned within a processing regionbecause the substrate is located adjacent the first reactive gas port125 and between two gas curtains 150 a, 150 b. Rotating the substrate 60along path 127 will move the substrate counter-clockwise around theprocessing chamber 100. Thus, the substrate 60 will be exposed to thefirst processing region 250 a through the eighth processing region 250h, including all processing regions between. For each cycle around theprocessing chamber, using the gas distribution assembly shown, thesubstrate 60 will be exposed to four ALD cycles of first reactive gasand second reactive gas.

The conventional ALD sequence in a batch processor, like that of FIG. 5,maintains chemical A and B flow respectively from spatially separatedinjectors with pump/purge section between. The conventional ALD sequencehas a starting and ending pattern which might result in non-uniformityof the deposited film. The inventors have surprisingly discovered that atime based ALD process performed in a spatial ALD batch processingchamber provides a film with higher uniformity. The basic process ofexposure to gas A, no reactive gas, gas B, no reactive gas would be tosweep the substrate under the injectors to saturate the surface withchemical A and B respectively to avoid having a starting and endingpattern form in the film. The inventors have surprisingly found that thetime based approach is especially beneficial when the target filmthickness is thin (e.g., less than 20 ALD cycles), where starting andending pattern have a significant impact on the within wafer uniformityperformance. The inventors have also discovered that the reactionprocess to create SiCN, SiCO and SiCON films, as described herein, couldnot be accomplished with a time-domain process. The amount of time usedto purge the processing chamber results in the stripping of materialfrom the substrate surface. The stripping does not happen with thespatial ALD process described because the time under the gas curtain isshort.

Accordingly, embodiments of the disclosure are directed to processingmethods comprising a processing chamber 100 with a plurality ofprocessing regions 250 a-250 h with each processing region separatedfrom an adjacent region by a gas curtain 150. For example, theprocessing chamber shown in FIG. 5. The number of gas curtains andprocessing regions within the processing chamber can be any suitablenumber depending on the arrangement of gas flows. The embodiment shownin FIG. 5 has eight gas curtains 150 and eight processing regions 250a-250 h. The number of gas curtains is generally equal to or greaterthan the number of processing regions. For example, if region 250 a hadno reactive gas flow, but merely served as a loading area, theprocessing chamber would have seven processing regions and eight gascurtains.

A plurality of substrates 60 are positioned on a substrate support, forexample, the susceptor assembly 140 shown FIGS. 1 and 2. The pluralityof substrates 60 are rotated around the processing regions forprocessing. Generally, the gas curtains 150 are engaged (gas flowing andvacuum on) throughout processing including periods when no reactive gasis flowing into the chamber.

A first reactive gas A is flowed into one or more of the processingregions 250 while an inert gas is flowed into any processing region 250which does not have a first reactive gas A flowing into it. For exampleif the first reactive gas is flowing into processing regions 250 bthrough processing region 250 h, an inert gas would be flowing intoprocessing region 250 a. The inert gas can be flowed through the firstreactive gas port 125 or the second reactive gas port 135.

The inert gas flow within the processing regions can be constant orvaried. In some embodiments, the reactive gas is co-flowed with an inertgas. The inert gas will act as a carrier and diluent. Since the amountof reactive gas, relative to the carrier gas, is small, co-flowing maymake balancing the gas pressures between the processing regions easierby decreasing the differences in pressure between adjacent regions.

One or more embodiments of the disclosure are directed to hardware gasinjector modules that provide multiple gas inlets and multiple gasremoval sections within a single module. The number of gas inlets andgas removal sections can be any combination. Some embodimentsadvantageously provide gas injector inserts that can be retrofit intoexisting gas distribution assemblies. One or more embodimentsadvantageously provide injector inserts that allow local gas exchangesand local high and low pressure regions within the modular injectorsegment.

One or more embodiments of the disclosure are directed to injectormodules or inserts that improve the removal of reaction by-product. Oneor more embodiments of the disclosure provide injector modules thatminimize or eliminate parasitic CVD that contributes to processnon-uniformity and lack of conformality. Some embodiments of thedisclosure provide modules that remove byproducts, target desorption ofgas trapping, improve deposition uniformity, improve conformality inhigher aspect ratio features, reduce in-film contaminates and/or reduceparticles.

One or more embodiments of the disclosure provide pump-purge sources(also referred to as segments and pie-shaped or wedge-shaped inserts)that provide additional high velocity purge gas on top of the wafer asthe wafer passes the segment. The high velocity purge gas advantageouslywashes unused precursor and reaction products/by-products from thesubstrate surface and process region of the processing chamber. In someembodiments, the pump-purge segment has four high velocity deliveryslots with a row of small ports each having super-sonic delivery gasjets that act like an air knife. Vacuum channels are positioned on thesides of the slots to exhaust gas and unwanted constituents. In someembodiments, the pump-purge source is modified to provide a highvelocity precursor flow.

One or more embodiments of the disclosure advantageously provide gasdelivery systems that deliver and remove chemicals to/from all parts ofdeeps structures on wafers with high surface area ratios compared toblanket wafers. Some embodiments advantageously provide rapidreplenishment of precursor concentration on top of the wafers to as toavoid loading issues which are seen with high surface area wafers.

The use of showerheads and injectors typically result in low velocity ofeither gas on the surface and the boundary layer has to be broken byeither spinning the wafer or moving the wafer at very high velocitieswithin the chamber, resulting in issues with reliability, chemicalseparation and mean wafer between cleans (MWBC). Some embodiments of thedisclosure provide injector segments with about four linear slotsproviding high velocity gas. The pie assembly of some embodimentscomprises three plates clamped together with suitable fasteners. A topplate interfaces with and seals to the Injector cooling plate andinterfaces with piping to provide gas and vacuum exhaust. A middlesandwiched plate can have porting for the supply gas and many throughholes for vacuum. A bottom plate provides about four angularly equallyspaced linear slots for gas delivery to the wafer and three mid-waylinear slots for vacuum exhaust. Some embodiments include a precursordelivery bottom plate that does not have any vacuum slots.

Some embodiments of the disclosure provide a module that can be used asan insert for the gas distribution assembly. For example, the injectorunit 122 illustrated in FIG. 2 can have the combination of pump andpurge channels described and can be installed in the gas distributionassembly to target regions where additional removal or purge or both ispositioned. This allows for disruption of the injector symmetry tocontrol the overall process.

FIG. 6 illustrates a gas distribution assembly 120 with four injectorunits 122 and four openings 610. The openings 610 can be occupied by aninjector insert (not shown) which will form a uniform component. Theopenings 610 illustrated include ledges 612 which are sized to supportan injector insert.

FIGS. 7 and 8 illustrate a gas injector insert 700 in accordance withone more embodiment of the disclosure. FIG. 7 shows a top perspectiveview of the insert 700 and FIG. 8 shows a bottom perspective view of theinsert 700. FIG. 9 shows the front face 711 of the insert 700. The gasinjector insert 700 includes a wedge-shaped housing 710 with a back face712 and a front face 711, an inner peripheral end 715 and an outerperipheral end 716 and a first side 713 and second side 714. The innerperipheral end 715 and outer peripheral end 716 define the length L andan elongate axis 717 that extends along the length L in the middle ofthe width of the housing 710. The first side 713 and second side 714define the width of the housing 710. The width increases from the widthW_(l) at the inner peripheral end 715 to the width W_(o) at the outerperipheral end 716, forming the wedge-shape (also called a pie-shape).

The housing 710 is sized to fit within the opening 610 in the gasdistribution plate 120. In some embodiments, as illustrated, the housing710 includes a top portion 702 and bottom portion 703 configured to forma flange 704. The flange 704 can be a separate component from theinjector insert 700 or integrally formed, as illustrated. The injectorinsert 700 of some embodiments can be lowered into opening 610 (see FIG.6) so that the flange 704 rests on ledge 612.

In some embodiments, the housing 710 of the gas injector insert 700 isconfigured so that the front face 711 of the gas injector insert 700 issubstantially coplanar with the front face 121 of the gas distributionplate 120 or injector unit 122. As used in this manner, the term“substantially coplanar” means that the front face 711 of the gasinjector insert 700 and the front face 121 of the gas distribution plate120 are coplanar within ±0.2 mm, ±0.15 mm, ±0.10 mm or ±0.05 mm.

Referring back to FIG. 7, the gas injector insert 700 of someembodiments has a first opening 706 and a second opening 707 in the backface 712. The openings 706, 707 can be connected to or configured to beconnectable to one or more of a gas source and/or a vacuum source (e.g.,vacuum pump or foreline). In some embodiments, there are two, three,four or more first openings 706. In some embodiments, there are two,three, four or more second openings 707. The locations of the firstopenings and second openings can be varied along the length and width ofthe insert 700.

FIG. 10 shows a cross-sectional view of the gas injector insert 700 ofFIG. 7 taken along line 10-10. In the cross-sectional view of FIG. 10,the second opening 707 is bisected and the first opening 706 is notvisible. The second opening 707 is in fluid communication with at leastone second slot 730 in the front face 711 of the gas injector insert700. The at least one second slot 730 has an elongate axis that extendsfrom the inner peripheral end 715 to the outer peripheral end 716. Itwill be understood that any of the slots can extend from a region nearthe inner peripheral end 715 to a region near the outer peripheral end716, as shown. The elongate axis extending from the inner peripheral endmeans that the elongate axis has an inner end 731 near the innerperipheral end 715 and an outer end 732 near the outer peripheral end716. The second slot 730 illustrated in FIG. 10 is formed as a lineargrouping of openings 733 in the front face 711. The term “slot” used inthis manner can be a recessed portion with openings within (as shown inFIG. 13), or a line of openings in a flat front face (as shown in FIG.10).

In some embodiments, the second opening 707 is in fluid communicationwith at least one plenum 735 through passage 738. The plenum 735 isconnected to and in fluid communication with the first slot 730 throughpassages 736. The passages 736 have plenum openings 737 at one end andfirst slot 730 at the other end. The volume of the plenum 735 istypically larger than the total volume of the passages 736 so that theflux through the passages 736 at the ends of the plenum is about thesame as at the center of the plenum.

FIG. 11 shows a cross-sectional view of the gas injector insert 700 ofFIG. 7 taken along line 11-11. The first opening 706 is in fluidcommunication with at least one second slot 720 in the front face 711 ofthe gas injector insert 700. The at least one second slot 720 has anelongate axis that extends from the inner peripheral end 715 to theouter peripheral end 716 of the housing 710. Stated differently, theelongate axis extends from an inner end 721 near the inner peripheralend 715 and an outer end 722 near the outer peripheral end 716.

In some embodiments, the first opening 706 is in fluid communicationwith at least one first plenum 725. The first plenum 725 is connected toand in fluid communication with the first slot 720 through passages 726.The volume of the first plenum 725 is typically larger than the totalvolume of the passages 726 so that the flux through the passages 726 atthe ends of the first plenum 725 is about the same as at the center ofthe first plenum. The first opening 706 of the illustrated embodiment isin fluid communication with the first plenum 725 through passage 724,cross passage 742 and passage 744. The first plenum has passage openings727 to form fluid communication with the passage 726. The passages 726have slot openings 728 to form fluid communication from the passages 726to the slot 720.

FIG. 11 also shows a partial view of a second opening 707 in fluidcommunication with a second plenum 735 and a cross passage 739. Thecross passage 739 provides fluid communication between the adjacentopenings that form the second plenum 735.

FIG. 12 shows a cross-sectional view of the gas injector insert 700 ofFIG. 7 taken along line 12-12. This view is taken through the secondopening 707 and shows passage 738 and cross passage 739 connecting theopening 707 to the second plenum 735.

FIG. 13 shows a cross-sectional view of the gas injector insert 700 ofFIG. 7 taken along line 13-13. This view is taken through the firstopening 706 and shows the passage 724, cross passage 742 and passage 744connecting the first opening 706 to the first plenum 725. In this view,the second plenum 735 and passage 736 to the second slot 730 are visiblewhile the second opening 707 is in a different plane. The first slot 720and second slot 730 illustrated in FIG. 13 shows recessed surfaces withsidewalls extending orthogonal to the surfaces. The slot opening 728 andslot opening 733 are located in the recessed surface of the slots and agas exiting the slots travels parallel to the sidewalls.

As will be understood by the skilled artisan, the use of the ordinaldescriptors for a first slot and second slot, or a first plenum andsecond plenum, do not imply a particular order of components. Rather,the ordinals illustrate the connected nature of the components. Forexample, each of the first slots will be connected to a first plenum(either the same plenum or different plenum) and each of the secondslots will be connected to a second plenum (either the same plenum ordifferent plenum). A substrate passing the gas injector insert 700 couldbe first exposed to either the first slot or the second slot and thelast exposure could be to either a first slot or a second slot.

The number of first slots 720 and second slots 730 can vary. In someembodiments, there are more first slots 720 than second slots 730. Insome embodiments, there are an equal number of first slots 720 andsecond slots 730. In some embodiments, there are four first slots 720and three second slots 730, as illustrated in FIGS. 8 and 9.

The shape of the slots can vary. In some embodiments, the first slots720 are linear slots having a substantially uniform width from the firstend 721 to the second end 722 of the first slots 720. In someembodiments, the second slots 730 are linear slots having asubstantially uniform width from the first end 731 to the second end732. In some embodiments, both the first slots 720 and second slots 730are linear slots. In some embodiments, one or more of the first slots720 or second slots 730 are wedge-shaped slots. As used in this manner,the term “substantially uniform” means that the width of the slot doesnot vary by more than 10%, 5%, 2% or 1% at any point along the elongatelength relative to the average width.

The order, arrangement and widths of the slots can vary to change theflow dynamics of the process chamber. For example, a combination ofvacuum and purge gas slots can create a gas curtain region to removeresidual reactive species from the process region. In some embodiments,the injector insert 700 is configured for use as a purge-pump system. Inembodiments of this sort, the first slots 720 are in fluid communicationwith a purge gas through the first opening 706 and the second slots 730are in fluid communication with a vacuum source through the secondopening 707. In some embodiments, each first slot 720 is spaced from anadjacent first slot 720 by a second slot 730.

In some embodiments, each of the first slots 720 extend at an angle tothe adjacent first slots 720. The angle between the first slots 720 canvary depending on, for example, the overall size (width and length) ofthe injector insert 700. In some embodiments, the first slots 720 are atan angle to the adjacent first slots 720 in the range of about 1° toabout 10°, or in the range of about 2° to about 8°, or in the range ofabout 3° to about 6°, or in the range of about 4° to about 5°. In someembodiments, the angle between adjacent first slots 720 is less than orequal to about 15°, 14°, 13°, 12°, 11°, 10°, 9°, 8°, 7°, 6°, 5°, 4°, 3°or 2°.

In some embodiments, the gas injector insert 700 is configured toprovide a flow of gas through the housing 710 from the first opening 706and exiting the first slots 720 at supersonic velocity. In someembodiments, the gas flow exiting the first slots 720 has a velocitygreater than or equal to about Mach 1, Mach 1.5, Mach 2, Mach 2.5, Mach3, Mach 3.5, Mach 4, Mach 4.5 or Mach 5. In some embodiments, theinjector insert 700 is configured to provide vacuum streams withsubsonic velocities.

In some embodiments, the housing 710 comprises a plurality of componentsassembled to form the injector insert 700. In some embodiments, as notedin FIG. 13, the wedge-shaped housing 710 comprises a top plate 800, anintermediate plate 900 and a bottom plate 1000.

FIG. 14 illustrates a top plate 800 in accordance with one or moreembodiment of the disclosure. The top plate 800 comprises at least onesecond opening 707 in the top face 801 that extends through thethickness of the top plate 800. The top face 801 of some embodimentsalso serves as the back face 712 of the housing 710. In someembodiments, the housing 710 is a separate component that surrounds thetop plate 800. The at least one second opening 707 is in fluidcommunication with a plurality of channels 820 formed in the bottom face802 of the top plate 800. When the top plate 800 is connected to theintermediate plate 900, the channels 820 in the bottom face 802 of thetop plate 800 form the second plenum 730 and cross passage 739.

The top plate 800 also includes at least one first opening 706 which isnot visible in the illustrated embodiment. The at least one firstopening 706 is in fluid communication with a plurality of passages 810,which are visible, extending through the top plate which will connectwith and form fluid communication with the intermediate plate 900.

FIG. 15A shows a top view of an intermediate plate 900. FIG. 15B shows abottom view of an intermediate plate 900 in accordance with one or moreembodiment of the disclosure. The intermediate plate 900 has a top face901 and bottom face 902 defining a thickness of the intermediate plate900. A plurality of first passages 910 extend through the intermediateplate 900 and are aligned with the plurality of passages 810 in the topplate 800. A plurality of second passages 736 extend through theintermediate plate 900 and are aligned with the plurality of channels820 in the top plate 800.

The bottom face 902 of the illustrated embodiment has a plurality ofridges 930 that extend a distance from the bottom face 902. The ridges930 extend from an inner end 903 to an outer end 904 of the intermediateplate 900. The ridges 930 of some embodiments, as illustrated, do notextend to the edges of the plate 900. Rather, the inner end 903 is aregion near the edge boundary of the plate 900 and the outer end 904 isa region near the edge boundary of the plate 900. Each of the pluralityof first passages 910 extend through the intermediate plate 900 to abottom face 932 of one of the ridges 930.

The ridges 930 of some embodiments have sidewalls 931 that extend alonga plane orthogonal to the plane formed by the bottom face 902 to abottom face 932 of the ridge 930. In some embodiments, as shown inexpanded view FIG. 15C, the plurality of ridges 930 have sloped sides931 or ends 935 so that the width W_(r) of the ridge 930 increases withdistance from the bottom face 902 of the intermediate plate 900. In someembodiments, the sloped sides 931 or ends 925 slope so that the widthW_(r) of the ridge 930 decreases with distance from the bottom face 902of the intermediate plate 900.

FIG. 16A shows a bottom plate 1000 in accordance with one or moreembodiment of the disclosure. The bottom plate 1000 illustrated has aplurality of first channels 1010 and a plurality of second openings 736in the top face 1001 of the bottom plate 1000. The plurality of firstchannels 1010 are aligned with the plurality of ridges 930 in theintermediate plate 900 so that when assembled, each ridge 930 is withina channel 1010. The plurality of channels 1010 are in fluidcommunication with the first slots 720 in the front face of the housing710. The plurality of second openings 1020 are aligned with theplurality of second passages 736 in the intermediate plate 900 andextend the second passages 736 through the thickness of the bottom plate1000 to the second slots 730.

In some embodiments, as shown in expanded view FIG. 16B, each of theplurality of channels 1010 has a post 1030 at a first end 1011 and asecond end 1012 of the channel 1010. The post 1030 is adjacent to theends of the channel with a gap 1032 between the sides 1035 of the post1030 and the inside face 1016 of the channel 1010. In some embodiments,the sides 1035 of the posts 1030 are sloped so that the width (diameter)of the post 1030 increases with distance from the top face 1031 of thechannel 1010. The gap 1032 of some embodiments is sized to support an0-ring (not shown) to help form a gastight seal when the plates areassembled. The channel 1010 includes a recessed portion 1015 which canform the first slots 720 or communicate with additional openings andpassages to form fluid communication with the first slots 720.

The top plate 800, intermediate plate 900 and bottom plate 1000 can beassembled to form the injector insert 700. The components can beconnected with a fastener 1100 (see FIG. 10) so that the bottom face 802of the top plate 800 contacts the top face 901 of the intermediate plate900, and the bottom face 902 of the intermediate plate 900 contacts thetop face 1001 of the bottom plate 1000.

FIG. 17A shows a top view and FIG. 17B shows a bottom view of a bottomplate 1700 for precursor delivery. The embodiment illustrated showsthree channels 1710 in the top face 1701 and three slots 1720 in thebottom face 1702 of the bottom plate 1700. The illustrated component canbe used with intermediate plates and top plates configured to providethree flow paths. The skilled artisan will recognize that this is merelyrepresentative of one possible configuration and should not be taken aslimiting the scope of the disclosure. In some embodiments, the precursordelivery bottom plate 1700 has four first slots 1720 and four firstchannels 1710. In some embodiments, the precursor delivery bottom plate1700 is configured to provide a flow of precursor or reactive gas atsupersonic velocity.

FIGS. 18A and 18B illustrate a gas injector insert 1800 with a singlepiece body 1810. As used in this manner, the term “single piece” meansthat the upper plenum and lower plenum are formed in a unitary piece ofmaterial. Additional components (e.g., end plugs) can be added. Thehousing 1810 has a front face 1811 and back face 1812. The housing 1800can an upper passage 1820 and a lower passage 1830 extending along theelongate axis of the housing 1810. FIG. 18A shows a cross-sectional viewof the insert 1800 passing through the upper passage 1820. FIG. 18B is across-sectional view of the insert 1800 passing through the lowerpassages 1830. The upper passage 1820 and lower passage 1830 can act asplenums for the individual gas flow paths.

The upper passage 1820 is in fluid communication with one of the firstopening 1806 or second opening 1807 in the back face 1811. The lowerpassage 1830 is in fluid communication with the other of the firstopening 1806 or second opening 1807 in the back face 1811. In theillustrated embodiments, the first opening 1806 is in fluidcommunication with the lower passage 1830 and the second opening 1807 isin fluid communication with the upper passage 1820.

The upper passage 1820 has a plurality of apertures 1840 in fluidcommunication with passages 1841 extending from the upper passage 1820to the opening 1842 in the front face 1811 of the housing 1810. The endsof the upper passage 1820 shown in cross-section are open. Another upperpassage 1820 is illustrated within the body of the housing 1810 withplugs 1821 in the ends. The plugs can be inserted after forming thepassages to provide a gastight seal. The passage shown in cross-sectionis in fluid communication with the passage within the body through crosspassage 1809 in fluid communication with the upper passages 1820 andsecond opening 1807. In some embodiments, there are more than one upperpassage 1820 connected by upper cross passages 1809.

The lower passage 1830 has a plurality of apertures 1850 in fluidcommunication with passages 1851 extending from the lower passage 1830to the opening 1852 in the front face 1811 of the housing 1810. The endsof the lower passage 1830 shows in cross-section are closed with plugs1831. Two additional lower passages with plugs 1830 are shown in thebody the housing 1810. The plugs can be inserted after forming the lowerpassages 1830 to form a gastight seal.

Passage 1863 is shown extending from the top face 1811 of the housing1810 to the lower passage 1830. The passage 1863 has a plug 1861 closingoff the end at the top face 1811. A cross passage 1808 extends from thefirst opening 1806 to the passage 1863 and makes fluid connection to thelower passage 1830. A plurality of apertures 1850 in the lower passage1830 form a fluid connection to the front face 1811 through passage 1851and opening 1852. In the illustrated embodiment, optional additionalcross passages 1870 are shown extending from lower passage 1830 toadjacent lower passages so that there is more than one lower passageconnected by the at least one lower cross passage 1870.

In the foregoing specification, embodiments of the disclosure have beendescribed with reference to specific exemplary embodiments thereof. Itwill be evident that various modifications may be made thereto withoutdeparting from the broader spirit and scope of the embodiments of thedisclosure as set forth in the following claims. The specification anddrawings are, accordingly, to be regarded in an illustrative senserather than a restrictive sense.

What is claimed is:
 1. A gas injector comprising: a top plate having atop face and bottom face defining a thickness of the top plate, an innerperipheral end and an outer peripheral end defining a length andelongate axis, and a first side and a second side defining a width, thewidth increasing from the inner peripheral end to the outer peripheralend, at least one first opening in the top face is in fluidcommunication with a plurality of passages extending through the topplate, and at least one second opening in the top face in fluidcommunication with at least one channel formed in the bottom face of thetop plate; an intermediate plate having a top face and a bottom facedefining a thickness of the intermediate plate, the top face positionedin contact with the bottom face of the top plate, a plurality of firstpassages extend through the thickness of the intermediate plate and arealigned with the plurality of passages in the top plate, and a pluralityof second passages extend through the thickness of the intermediateplate and are aligned with the at least one channel formed in the bottomface of the top plate; and a bottom plate having a top face and a bottomface defining a thickness of the bottom plate, the top face of thebottom plate in contact with the bottom face of the intermediate plate,a plurality of first channels in the top face of the bottom platealigned with the plurality of first passages in the intermediate plate,the plurality of first channels in fluid communication with at least onefirst slot in the bottom face of the bottom plate, the at least onefirst slot extending from a first end near an inner peripheral end ofthe bottom plate to a second end near an outer peripheral end of thebottom plate, and a plurality of second openings in the top face of thebottom plate aligned with the at lest one channel in the bottom face ofthe intermediate plate, the plurality of second openings in fluidcommunication with at least one second slot formed in the bottom face ofthe bottom plate, the at least one second slot extending from the firstend to the second end of the bottom plate.
 2. The gas injector of claim1, wherein each of the first slots is spaced from adjacent first slotsby a second slot and a gas flowing through the first slot exits thefirst slot at supersonic velocity.
 3. The gas injector of claim 2,wherein there are more first slots than second slots.
 4. The gasinjector of claim 3, wherein there are four first slots and three secondslots.
 5. The gas injector of claim 4, wherein the first slots arelinear slots having a substantially uniform width from the first end tothe second end.
 6. The gas injector of claim 5, wherein the second slotsare linear slots having a substantially uniform width from the first endto the second end.
 7. The gas injector of claim 1, wherein the gasinjector insert is configured to provide a flow of gas from the firstopening and exiting the first slots at supersonic velocity.
 8. The gasinjector of claim 7, wherein the first slots are in fluid communicationwith a purge gas and the second slots are in fluid communication with avacuum source.
 9. The gas injector of claim 1, wherein the bottom faceof the intermediate plate comprises a plurality of ridges extending froman inner end to an outer end, each of the plurality of first passagesextending to a bottom face of one of the ridges.
 10. The gas injector ofclaim 9, wherein the plurality of ridges have sloped sides so a width ofthe ridges increases with distance from the bottom face of theintermediate plate.
 11. The gas injector of claim 10, wherein the bottomplate has a first plurality of channels and a second plurality ofopenings in a top face of the bottom plate, the first plurality ofchannels aligned with the plurality of ridges in the intermediate plateso that when assembled, each of the ridges is within a channel, theplurality of channels in fluid communication with the first slots in thebottom face of the bottom plate, the second plurality of openingsaligned with the plurality of second passages in the intermediate plateand extending through a thickness of the bottom plate to second slots inthe bottom face of the bottom plate.
 12. The gas injector of claim 11,wherein each of the plurality of channels in the bottom plate have apost adjacent a first end and a second end of the channels.
 13. The gasinjector of claim 1, wherein the top plate, intermediate plate andbottom plate are connected by a fastener so that a bottom face of thetop plate contacts a top face of the intermediate plate and a bottomface of the intermediate plate contacts a top face of the bottom plate.14. The gas injector of claim 13, where there are more than one upperpassage connected by at least one upper cross passage and there is morethan one lower passage connected by at least one lower cross passage.